The rate of evaporation in kg/h m2 can be estimated for the swimming
pool in normal activity, integrating splashing due to the bathes
on the accesses of a limited zone (Smith, et al., 1993) (ASHRAE,
1995), according to the following formula:

W = Rate of evaporation at the surface of the water level (kg/h
m2)

Pw = Vapor pressure at saturation taken at the temperature of
surface of water, in kPa

Pa = Vapor pressure at the dew point according to the temperature
of the ambient air of the room, in kPa

V = Air velocity above at the surface of water, in m/s

Y = Latent heat necessary according to the change of state of
the water vapor at the temperature of surface of water, in kJ/kg

Function = Pool_evap1(ts1, ts, Hr, Saw, Z)
- ts = Dry temperature in °C of the ambient air of the swimming
pool
- ts1 = Temperature in °C at the water level
- Hr = relative Humidity in %
- Vit = Air velocity in m/s at the level of water
- Z = Altitude in m

Evaporation in swimming polls in kg/h m2 according to the
type of activity in the covered swimming pools

For a latent heat (Y) of a value of 2330 kJ/kg and with a speed
of air (V) at 0,10 m/s and while multiplying by a factor of activity
(Fa) to reduce the rate of evaporation estimated according to the
corresponding level of activity, the equation is reduced to the
following expression:

W = Rate of evaporation at the surface of the water level (kg/h
m2)

Pw = Vapor pressure at saturation taken at the temperature of
surface of water, in kPa

Pa = Vapor pressure at the dew point according to the temperature
of the ambient air of the room, in kPa

Type of swimming pools

Factor of activity (Fa)

Residential swimming pools

0.5

Condominium

0.65

Thermal baths

0.65

Hotel

0.8

Public swimming pools or Schools

1

Whirlpools, spas

1.5

Wave pools, water slides

1.5 (minimum)

Evaporation at the level of water in kg/h m2
- ts = Dry temperature in °C of the ambient air of the swimming
pool
- ts1 = Temperature in °C at the level of water
- Hr = Relative humidity in %
Function = Pool_evap2(ts1, ts, Hr)

Evaporation at the level of water in kg/h m2 (another formula)

Evaporation at the water level in kg/h m2

W = Rate of evaporation at the surface of the water level (kg/h
m2)

We = water content of the air at the temperature of the water
level (kg/kg of dry air)

Wa = water content of the air of the room (kg/kg of dry air)

V = Specific volume of the air in the room (m3/kg of dry air)

Vµ = Specific volume of the air at the level of water
(m3/kg of dry air)